The present disclosure relates to spin torque oscillators (STO) in magnetic field-assisted recording (MAMR) heads, in which a spin torque oscillator is formed in the write gap, and a high frequency magnetic field is applied to the recording medium in order to reduce the coercive force of the medium, and in this state, apply a recording field to the medium to record data. One challenge with conventional MAMR heads is that electrical current overshoots in the write coils coupled to the main magnetic pole increase the switching field threshold in the magnetic medium, leading to insufficient MAMR assist gain to achieve sufficient recording width and good write-ability. Conventional pulse assist technology in MAMR heads has failed to adequately address the decreased MAMR assist gain associated with the current overshoots in the write coils.
Another challenge with conventional spin torque oscillators is that the small size of the STO is correlated with a bias heating that is significantly high, surpassing 200° C., which may lead to oxidation and performance degradation. While heat sinks and larger STO sizes somewhat mitigate this temperature rise, temperature control is still limited with these approaches, thereby compromising STO performance. Other conventional MAMR heads have addressed this problem with a direct bias current that is constantly applied on the STO during recording. However, this constant application of direct current on the STO leads to significant heat generation, thereby also compromising STO performance.